A group of helical gears are part of a helical gearbox. One type of cylindrical gear that has a slanted tooth trace is called a helical gear. They excel in quietness, have a lower vibration level, and can transfer more loads than spur gears. A set of helical gears has the same helix angle, but the helix hand is on the other side. By tilting the hobbing instrument, the spur gear hobbing tool and hobbing machine can be used to make helical gears when the reference section of the gear is in the standard shape. Teeth are produced with the drawback of more difficult construction because of their twist.